lokinet/vendor/cppbackport-master/lib/fs/basename.cpp

/* Copyright (c) 2014, Pollard Banknote Limited
   All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are met:

   1. Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.

   2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

   3. Neither the name of the copyright holder nor the names of its contributors
   may be used to endorse or promote products derived from this software without
   specific prior written permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
   LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   POSSIBILITY OF SUCH DAMAGE.
 */
#include "basename.h"

#include "../config/os.h"
#include "cleanpath.h"

namespace
{
  // the position following the previous occurrence of c (relative to position
  // j), or 0 if not. In this file, the first letter of a path component.
  std::size_t
  after_last(const std::string& s, char c, std::size_t j)
  {
    std::size_t i = s.find_last_of(c, j);

    return i == std::string::npos ? 0 : i + 1;
  }

  // (first character, length) of last path component in s or (0,0) for "."
  // or (npos, 0) if error
  std::pair< std::size_t, std::size_t >
  locate_last_path_component(const std::string& s)
  {
    if(s.empty())
    {
      // error
      return std::pair< std::size_t, std::size_t >(std::string::npos, 0);
    }

    // j points to the last character in a component
    std::size_t j  = s.find_last_not_of('/');
    unsigned depth = 0;

    while(j != std::string::npos)
    {
      // i points to first character of a component
      // i <= j, because j never points to a '/'
      const std::size_t i = after_last(s, '/', j);

      if(j - i + 1 == 1 && s[i] == '.')
      {
        // component is ".", basically ignore this component
      }
      else if(j - i + 1 == 2 && s[i] == '.' && s[i + 1] == '.')
      {
        // component is "..", ignore the next component
        ++depth;
      }
      else
      {
        // found a "normal" path component
        if(depth == 0)
        {
          return std::pair< std::size_t, std::size_t >(i, j - i + 1);
        }

        // ..but we're ignoring it
        --depth;
      }

      if(i == 0)
      {
        if(depth == 0)
        {
          // "."
          return std::pair< std::size_t, std::size_t >(0, 0);
        }
        else
        {
          // error, path is malformed
          return std::pair< std::size_t, std::size_t >(std::string::npos, 0);
        }
      }

      j = s.find_last_not_of('/', i - 1);
    }

    // all slashes
    return std::pair< std::size_t, std::size_t >(0, 1);
  }

  std::string
  basename_posix(const std::string& s)
  {
    const std::pair< std::size_t, std::size_t > range =
        locate_last_path_component(s);

    if(range.first == std::string::npos)
    {
      return std::string();
    }

    if(range.first == 0 && range.second == 0)
    {
      return ".";
    }

    return s.substr(range.first, range.second);
  }
  std::string
  dirname_posix(const std::string& s)
  {
    const std::pair< std::size_t, std::size_t > range =
        locate_last_path_component(s);

    // path was malformed
    if(range.first == std::string::npos)
    {
      return std::string();
    }

    if(range.first == 0)
    {
      if(range.second == 0)
      {
        return "..";
      }

      // could be '/', or could be a unpathed filename
      if(s[0] == '/')
      {
        return "/";
      }

      return ".";
    }
    else
    {
      // leading directory
      return s.substr(0, range.first);
    }
  }

}  // namespace

namespace cpp17
{
  namespace filesystem
  {
    // Calls the basename_xxx appropriate for this platform
    std::string
    basename(const std::string& s)
    {
#ifdef OS_POSIX
      return basename_posix(s);
#else
      std::string t;
      char fname[_MAX_FNAME], ext[_MAX_EXT];
      _splitpath(s.c_str(), nullptr, nullptr, fname, ext);
      t = fname;
      t += ext;
      return t;
#endif
    }

    std::string
    dirname(const std::string& s)
    {
#ifdef OS_POSIX
      const std::string& t = dirname_posix(s);

      if(t == ".")
      {
        return t;
      }

      return cleanpath(t);

#else
      std::string t;
      char _dirname[_MAX_DIR];
      _splitpath(s.c_str(), nullptr, _dirname, nullptr, nullptr);
      t = _dirname;
      return t;
#endif
    }

  }  // namespace filesystem
}  // namespace cpp17